2.2.2 Disjunction

Disjunction is represented as follows:

• programming: or for most languages that are not derived from C, || for most C-derived languages.
• engineering: +.
• mathematics: ∨. This is the symbol we’ll use in this module.

Like conjunction, disjunction is a relation and a function. As a relation, ∨⊆ 𝔹 × 𝔹 × 𝔹. The individual elements of the relation is as follows:

• (true,true,true)
• (true,false,true)
• (false,true,true)
• (false,false,false)

Like conjunction, disjunction is also commutative and associative. The identity of disjunction is false, as ∀A ∈ 𝔹 : A ∨ false = A. As a function, disjunction is also non-injective but surjective.